In /srv/ghost copy config.example.js to config.js and modify the beginning to meet your needs. Two additional parameters need to be added to the default config for SSL support. Here is an example snippet of the modified production section.

It will be listening on 127.0.0.1:2368 by default which is perfect for passing to from Nginx.

If you haven't gotten your SSL certificate yet at this point and want a quick refresh, check out my post on generating a CSR for a quick example using Comodo's PositiveSSL.

The following is an example nginx configuration for proxying requests to our Ghost installation. I prefer a naked domain myself so you'll notice the redirects here. If you are unfamiliar with the implications of that this site has a great breakdown with example configurations for you to work with.